This invention relates to a method and apparatus for assessing quality of service for communication networks. More particularly, the invention is directed to assessing quality of service in circuit and packet switched networks by way of a computer simulation. Preferably, the information necessary to conduct the assessment activity is available via the internet from a web server that also compiles statistical data on the resultant quality of service assessments.
While the invention is particularly directed to the art of assessing quality of service for communication networks, and will be thus described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications. For example, the invention may be used in any system where quality of service issues arise such as on local area networks and the like.
By way of background, phone companies historically performed expensive tests to determine network interface rules for the North American market. This included subjective statistical Quality of Service tests to determine subscriber tolerances relating to communications signal levels, distances, echo, phone sets, etc. From this data, interface rules were established concerning ranges for acceptable db loss and related latency delays and the distances between network components.
More particularly, prior manners of network planning and design can be better understood by referring to FIGS. 1 and 2. In FIG. 1, it is shown that individual components C in a path between users U contribute to latency time delays as illustrated throughout the network path. The total time delay between the users, as shown, is 33 ms. These time delays are directly related to echoes that can be heard by the users and, of course, impact the Quality of Service to the users. Such impact is illustrated in FIG. 2 wherein a rating factor (measuring voice transmission and quality) is plotted versus the time delay. It can be seen that as the time delay increases, user satisfaction decreases.
It is to be appreciated that well known network devices may be implemented that decrease these latency time delays. However, to test networks during the design process to determine the necessity and/or sufficiency of such devices, there was heretofore available only the above-mentioned, costly physical network tests.
Moreover, with the restructuring of the telecommunications industry, Quality of Service planning and evaluation has become an increasingly complex arena. For example, new packet technology, such as IP/TCP-ATM, changes the shipment and arrival time interval of spoken words and compression and decompression chips remove quiet-time, degrade the signal and add latency delay. This all supports the need for improved Quality of Service techniques that are economical, will allow for customer use on a convenient network such as the World Wide Web (WWW), and will enhance product understanding and sales.
The present invention contemplates a method and apparatus for assessing quality of service for communication networks that resolve the above-referenced difficulties and others.